Help - Scanned outline to part

[revwarguy]

Hello,

I am just completing the build of a CNC router table, so I am a real newbie. I am no stranger to software, but new to CAM. I have purchased Mach 3 and Cambam on a recommendation.

I have a need to take a piece of cardboard or paper that is the exact cutout of a part, scan it into the computer, and have it cut out a 2D part following that outline. Material is like 1/4 inch plywood, etc. I have a lot of these to do, so the process needs to be as simple as possible.

I have tried 1. cleaning the scan up in Photoshop, 2. rasterizing it with Illustrator and exporting it to dxf, 3. then importing it into Cambam, and 4. converting everything to polylines.

This seems clumsy, error prone and problematic because I have to take it to a friend who has the Photoshop suite as I do not have it. I've tried Lazycam (came with Cambam) but I can't seem to get it to do anything useful.

Can someone recommend a better, simpler way to do this? If suggesting new software, could you describe the steps, and the cost of the software? (Price is important here.)

TIA,

[metalworkz]

Hello,
Is each one you need to do different than the first one? In other words you will need to scan each one and do the whole process each time?
I have had good luck with scans of both the profiles of the part traced onto the cardboard and of the actual profile of the cardboard edge, but I think the lines may provide a better vector when scanned. The less work you need to do after scanning the better. The scanning usually works good but if the software is allowed to trace the image it will probably throw a lot of misc. garbage into the trace that will need to be edited out. Sometimes you can manually trace the lines and end up with a cleaner finished .dxf than if you leave it up to the software.
Another option is to dimension the part and draw it in CAD. Once you get proficient with the CAD program you will find it does not take too long, and after seeing poor results from software traces and all the work it takes to clean it up you may find it easier to draw it, expecially if it is just 2D.
There are some decent tracing programs that do a good job, but you mentioned price is important. I think the best choice for a program that traces very well and offers great drawing tools and also excellent toolpath generation with previews you will have a hard time beating VCarvePro from Vectric. It also has nesting ability in the new version. Check out their trial versions:
www.vectric.com

There are free programs that will allow you to trace like Inkscape, and you can use Gimp for working with the raster images. For a good source of information with the price point of 'Free' you should take a look at Yohudi's (Danny Lewis) web site:
http://cnc4free.org/
He has links to all the software he recommends and tutorials on how to use them.

I hope something I have posted will help you!

[One of Many]

I don't know the programs of which you mentioned, but I have had decent luck with a standard scanner to import JPEG images into AutoCad. Once I have it imported, I can scale to approximate size, then use that for overlay drawings to get my geometry associative. If need be, I tune the scale factor after I have a rough idea on the dimensions and layout.

Use a Sharpie or some other felt marker to give the cardboard template(or whatever) edges plenty of contrast, does help a lot for this method.

Splines do not always work out well in some CAM software DXF transfers, so getting the tangent arcs to work out in the overlay DWG can be a bit of a hassle. No big deal once you get comfortable with how the software works for a clean result. On symmetrical parts, I prefer to work about a centerline, so at some point I can mirror that half to the opposite side to keep things true to form.

At least after having a true to dimension geometry with fewer inherant flaws, I have a lot more confidence in putting a cutter to material with less odds of scrap.

If you need profiles tolerances closer than what an image to DXF overlay can give, you might consider using your machine with an edge finder like a suedo-CMM and grab coordinates off the screen to reduce the errors the jpeg image will generate in profile resolution. Just don't forget the edge finder or probe radius when using those coordinates to generate geometry in your CAD program.

DC